Aging Treatment Characteristics of Shear Strength in Micro Solder Bump

Abstract

The shear strength of the Cr/Cr–Cu/Cu UBM structure in both the high-melting solder bump and low-melting solder bump after aging were evaluated. SEM and TEM were examined in the intermetallic compounds and bump joint profiles at the interface between solder and UBM . The shear load concentrated on the bump was analyzed by finite element method. In 900-hour aging experiments, the maximum shear strength of Sn–97 mass%Pb and Sn–37 mass%Pb decreased by 25% and 20%, respectively. The growth of Cu₆Sn₅ and Cu₃Sn was ascertained by the aging treatment. The crack path changes from the interior of a solder to the intermetallic compound interface was evaluated. Compared with the Cu–Sn IMC, the amount of Ni–Sn IMC was small. The Ni layer is considered as the diffusion barrier.